The patch below does not apply to the 5.10-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.10.y git checkout FETCH_HEAD git cherry-pick -x 21a741eb75f80397e5f7d3739e24d7d75e619011 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024070820-relapse-humbly-3545@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:

21a741eb75f8 ("powerpc/pseries: Fix scv instruction crash with kexec") 2ab2d5794f14 ("powerpc/kasan: Disable address sanitization in kexec paths") e6f6390ab7b9 ("powerpc: Add missing headers") 3ba4289a3e7f ("powerpc: Simplify and move arch_randomize_brk()") ce0091a0e060 ("powerpc/time: Fix sparse warnings") 387e220a2e5e ("powerpc/64s: Move hash MMU support code under CONFIG_PPC_64S_HASH_MMU") 20626177c9de ("powerpc: make memremap_compat_align 64s-only") ffbe5d21d10f ("powerpc/64: pcpu setup avoid reading mmu_linear_psize on 64e or radix") f43d2ffb47c9 ("powerpc/64s: Rename hash_hugetlbpage.c to hugetlbpage.c") 162b0889bba6 ("powerpc/64s: move THP trace point creation out of hash specific file") 3d3282fd34d8 ("powerpc/pseries: lparcfg don't include slb_size line in radix mode") 0c7cc15e9215 ("powerpc/pseries: move process table registration away from hash-specific code") 7ebc49031d04 ("powerpc: Rename PPC_NATIVE to PPC_HASH_MMU_NATIVE") 6e5772c8d9cf ("Merge tag 'x86_cc_for_v5.16_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 21a741eb75f80397e5f7d3739e24d7d75e619011 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin npiggin@gmail.com Date: Tue, 25 Jun 2024 23:40:47 +1000 Subject: [PATCH] powerpc/pseries: Fix scv instruction crash with kexec

kexec on pseries disables AIL (reloc_on_exc), required for scv instruction support, before other CPUs have been shut down. This means they can execute scv instructions after AIL is disabled, which causes an interrupt at an unexpected entry location that crashes the kernel.

Change the kexec sequence to disable AIL after other CPUs have been brought down.

As a refresher, the real-mode scv interrupt vector is 0x17000, and the fixed-location head code probably couldn't easily deal with implementing such high addresses so it was just decided not to support that interrupt at all.

Fixes: 7fa95f9adaee ("powerpc/64s: system call support for scv/rfscv instructions") Cc: stable@vger.kernel.org # v5.9+ Reported-by: Sourabh Jain sourabhjain@linux.ibm.com Closes: https://lore.kernel.org/3b4b2943-49ad-4619-b195-bc416f1d1409@linux.ibm.com Signed-off-by: Nicholas Piggin npiggin@gmail.com Tested-by: Gautam Menghani gautam@linux.ibm.com Tested-by: Sourabh Jain sourabhjain@linux.ibm.com Link: https://msgid.link/20240625134047.298759-1-npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au

diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c index 85050be08a23..72b12bc10f90 100644 --- a/arch/powerpc/kexec/core_64.c +++ b/arch/powerpc/kexec/core_64.c @@ -27,6 +27,7 @@ #include <asm/paca.h> #include <asm/mmu.h> #include <asm/sections.h> /* _end */ +#include <asm/setup.h> #include <asm/smp.h> #include <asm/hw_breakpoint.h> #include <asm/svm.h> @@ -317,6 +318,16 @@ void default_machine_kexec(struct kimage *image) if (!kdump_in_progress()) kexec_prepare_cpus();

+#ifdef CONFIG_PPC_PSERIES + /* + * This must be done after other CPUs have shut down, otherwise they + * could execute the 'scv' instruction, which is not supported with + * reloc disabled (see configure_exceptions()). + */ + if (firmware_has_feature(FW_FEATURE_SET_MODE)) + pseries_disable_reloc_on_exc(); +#endif + printk("kexec: Starting switchover sequence.\n");

/* switch to a staticly allocated stack. Based on irq stack code. diff --git a/arch/powerpc/platforms/pseries/kexec.c b/arch/powerpc/platforms/pseries/kexec.c index 096d09ed89f6..431be156ca9b 100644 --- a/arch/powerpc/platforms/pseries/kexec.c +++ b/arch/powerpc/platforms/pseries/kexec.c @@ -61,11 +61,3 @@ void pseries_kexec_cpu_down(int crash_shutdown, int secondary) } else xics_kexec_teardown_cpu(secondary); } - -void pseries_machine_kexec(struct kimage *image) -{ - if (firmware_has_feature(FW_FEATURE_SET_MODE)) - pseries_disable_reloc_on_exc(); - - default_machine_kexec(image); -} diff --git a/arch/powerpc/platforms/pseries/pseries.h b/arch/powerpc/platforms/pseries/pseries.h index bba4ad192b0f..3968a6970fa8 100644 --- a/arch/powerpc/platforms/pseries/pseries.h +++ b/arch/powerpc/platforms/pseries/pseries.h @@ -38,7 +38,6 @@ static inline void smp_init_pseries(void) { } #endif

extern void pseries_kexec_cpu_down(int crash_shutdown, int secondary); -void pseries_machine_kexec(struct kimage *image);

extern void pSeries_final_fixup(void);

diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index cba40d9d1284..b10a25325238 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c @@ -1159,7 +1159,6 @@ define_machine(pseries) { .machine_check_exception = pSeries_machine_check_exception, .machine_check_log_err = pSeries_machine_check_log_err, #ifdef CONFIG_KEXEC_CORE - .machine_kexec = pseries_machine_kexec, .kexec_cpu_down = pseries_kexec_cpu_down, #endif #ifdef CONFIG_MEMORY_HOTPLUG